H13 steel surfaces are covered by coatings of Co-based alloy with 0, 10, 20, and 30 wt. % TiC using the laser cladding (LC) method. The morphological characteristics, growth mechanism, and the mechanical properties of TiC on the microstructure of the coatings were studied. The results show that TiC in the TiC/Co50 composite coating is composed of two parts: incompletely melted TiC and in situ TiC. TiC content has a great effect on the morphology of TiC, and it exists in different shapes: original TiC, fine-particle TiC, segregated TiC, petal-shaped TiC, and branch-shaped TiC. Additionally, the morphology of TiC in different areas of the coating is different, while TiC size gradually increases from bonding zone to surface. In the 10% TiC+Co50 coating, TiC mainly appears as undermelted, fine particles, precipitates, and having shapes of polygons and petals. From the bottom of this coating, the number of petal-shaped TiC has increased, and the particle size is also enlarged. In the 20% TiC+Co50 coating, the TiC in the coating mainly presents as undermelted, fine particles, and dendritic morphology. From the bottom of this coating to the surface, the particle size of the undermelted TiC shows a clear gradient change. Finally, the 30% TiC+Co50 coating does not have in situ TiC, and there is no obvious gradient change in the particle size of undermelted TiC. After coating by the LD method, the surface hardness is strongly enhanced. The average hardness of Co50 alloy, Co+10% TiC, and Co+20% TiC composite coatings is 499 HV_0.2, 552 HV_0.2, 590 HV_0.2, and 824 HV_0.2, respectively. These values are 2.4–4.0 times harder than that of the H13 substrate. The wear resistance of Co50 alloy, Co+10% TiC, and Co+20% TiC composite coatings is greatly higher than that of H13 steel, showing excellent wear characteristics. The friction coefficient of the coatings which have TiC is very stable. Therefore, the coatings can satisfy the requirement of tool steels applications. Additionally, the wear mechanism of the coating at room temperature is mainly brittle spalling, adhesive, and ploughing. At 700°C, the wear mechanism is mainly oxidation and fatigue.

中文翻译：

---

激光熔覆在Co50基涂层上TiC颗粒的行为：形态特征和生长机理

H13钢表面覆盖有0、10、20和30重量％的Co基合金涂层。使用激光熔覆（LC）方法的％TiC。研究了TiC在涂层微观结构上的形貌特征，生长机理和力学性能。结果表明，TiC / Co50复合涂层中的TiC由两部分组成：未完全熔融的TiC和原位TiC。TiC含量对TiC的形态有很大的影响，并以不同的形状存在：原始TiC，细颗粒TiC，偏析TiC，花瓣状TiC和分支状TiC。另外，在涂层的不同区域中TiC的形态是不同的，而TiC的大小从结合区到表面逐渐增大。在10％TiC + Co50涂层中，TiC主要表现为熔融不足，细小颗粒，沉淀，并具有多边形和花瓣的形状。从该涂层的底部开始，花瓣状TiC的数量增加，并且粒径也增大。在20％TiC + Co50涂层中，涂层中的TiC主要表现为熔融不足，细小颗粒和树枝状形态。从该涂层的底部到表面，未熔融的TiC的粒径显示出明显的梯度变化。最后，30％TiC + Co50涂层没有原位TiC，并且欠熔融TiC的粒径没有明显的梯度变化。通过LD法涂布后，表面硬度大大提高。Co50合金，Co ​​+ 10％TiC和Co + 20％TiC复合涂层的平均硬度为499 HV 在20％TiC + Co50涂层中，涂层中的TiC主要表现为熔融不足，细小颗粒和树枝状形态。从该涂层的底部到表面，未熔融的TiC的粒径显示出明显的梯度变化。最后，30％TiC + Co50涂层没有原位TiC，并且欠熔融TiC的粒径没有明显的梯度变化。通过LD法涂布后，表面硬度大大提高。Co50合金，Co ​​+ 10％TiC和Co + 20％TiC复合涂层的平均硬度为499 HV 在20％TiC + Co50涂层中，涂层中的TiC主要表现为熔融不足，细小颗粒和树枝状形态。从该涂层的底部到表面，未熔融的TiC的粒径显示出明显的梯度变化。最后，30％TiC + Co50涂层没有原位TiC，并且欠熔融TiC的粒径没有明显的梯度变化。通过LD法涂布后，表面硬度大大提高。Co50合金，Co ​​+ 10％TiC和Co + 20％TiC复合涂层的平均硬度为499 HV 熔融TiC的粒径没有明显的梯度变化。通过LD法涂布后，表面硬度大大提高。Co50合金，Co ​​+ 10％TiC和Co + 20％TiC复合涂层的平均硬度为499 HV 熔融TiC的粒径没有明显的梯度变化。通过LD法涂布后，表面硬度大大提高。Co50合金，Co ​​+ 10％TiC和Co + 20％TiC复合涂层的平均硬度为499 HV_0.2，552 HV _0.2，590 HV _0.2，和824 HV _0.2，分别。这些值是H13基板的2.4-4.0倍。Co50合金，Co ​​+ 10％TiC和Co + 20％TiC复合涂层的耐磨性大大高于H13钢，显示出优异的耐磨性。具有TiC的涂层的摩擦系数非常稳定。因此，该涂层可以满足工具钢应用的要求。另外，涂层在室温下的磨损机理主要是脆性剥落，粘附和起伏。在700°C下，磨损机理主要是氧化和疲劳。